Jacking means for building construction



Sept 4, 1962 J. c. L oNG ET AL 3,052,449

JACKING MEANS FOR BUILDING CONSTRUCTION Filed Oct. 6, 1958 7Sheets-Sheet 1 ATTORNEY Sept. 4, 1962 J. LONG ET AL 3,052,449

JACKING MEANS FOR BUILDING CONSTRUCTION Filed Oct. 6, 1958 7Sheets-Sheet 2 ATTORNEYS Sept. 4, 1962 J. c. LONG ET AL 3,952,449

JACKING MEANS FOR BUILDING CONSTRUCTION.

Filed Oct. 6, 1958 '7 Sheets-Sheet 3 INVENTOR dof/,v l 0,1/6

ATTORNEY5 sept. 4, 1962 Filed Oct. 6, 1958 J. C. LONG ET AL 7Sheets-Sheet 4 9 5- @J Q 54 f7 fm Z6 --V-YN-wil NZ "V mil' "I-l/INVENTORS n/O/f/v [0A/6 /MMW A/M@ ATTORNEY;

Sept. 4, 1962 J. c. LONG ET AL 3,052,449

JACKING MEANS FOR BUILDING CONSTRUCTION Filed Oct. 6, 1958 '7SheeLS-Sheet 5 yff/.MAMV ggf n L! .y mi l'.

BY www@ ATTORNEYS Sept. 4, 1962 J. c. LONG ETA. 3,052,449

JACKING MEANS FOR BUILDING CONSTRUCTION Filed oct. e, 1958 7sheets-sheet 6 l I I I "1 l I Nn I l\| I I l Irl I I J INVENTOR /0f//v C0A/6 ATTORNEYS Sept. 4, 1962 J. c. LoNG ETAL 3,052,449

JACKING MEANS FOR BUILDING CONSTRUCTION Filed OCI. e, 1958 frsheets-sheet fr /`/6` on of 6 *Y INVENTORS ATTORNEY 3,052,449 JACKINGMEANS FOR BUILDING CONSTRUCTION .lohn C. Long, 90 Broad St., and LeonardD. Long, Klug and Mount Pleasant Sts., both of Charleston, S.C. FiledOct. 6, 1958, Ser. No. 765,499 3 Claims. (Cl. 254-89) This inventionrelates to building construction and particularly to methods andapparatus for the economic and speedy construction of buildings havingconcrete roofs and intermediate oors.

Prior to the invention, although the desirability of concrete roofs andintermediate oors has been accepted, there was no available manner ofeconomically incorporating such structure into small buildings. Usuallythis involved the following requirement. First `framing t hold the roofor floor was required. This has usually been accomplished by means ofwood posts or supports upon which was placed plywood or some other typeof wood decking. Reinforcing was placed on top of the decking and thenconcrete poured onto the decking. After a given number of days, usually28 or more, the supports and forming were removed. In using the woodposts or supports and the plywood forming to hold the concrete, it -wasnecessary that the thickness of the concrete be s0 large and thereinforcing be so increased so that there would be a clear span afterthe forming was removed, and it was practically impossible to build wallsupports under the concrete roofs or iloors while the wooden supportsremained in place. The eXtra concrete and reinforcing to create theclear span greatly increased the costs of the concrete roofs andsometimes made them impractical.

The expense of placing the reinforcing and the concrete into the formsfor the roof or upper oor was a material factor to be considered, for inthe construction industry every item of material or work above groundlevel increases costs of construction. Another factor that had to beconsidered in the construction of concrete roofs or upper oors in aconventional manner of supporting the roof or upper floor by woodframing and wood supports and the use of plywood for the forming of Samewas the fact that it is literally impossible to secure a proper finishon the underside of the concrete roof or upper oor due to the jointsbetween the plywood forming.

Another factor that had to be considered in the construction of roofsand upper floors in a conventional onto the floors below, due either tospillage while placing J the concrete on the roof or upper iloor or theleaking of the cement through the joints in the plywood. Therefore,unless the spillage of the concrete was immediately removed, whichproved awkward working between the wooden supports of the roof or upperfloor, it would adhere to the lower oor, necessitating the removal ofthe same with scars on the lower floor.

In the conventional manner of constructing a concrete roof or upperfloor, there was also the considerable eX- pense of placing the framingand plywood forms in place, the removal of the forms and thedepreciation of the forms due to damage by use. It has been estimatedthat Wood forms cannot be used more than eight times, and this proved anexpensive factor in itself, without the other additional costs ofconstructing concrete roofs and the like in a conventional manner, allof which has heretofore precluded the use of concrete roofs and upperfloors in the lower price range of construction.

The invention is particularly directed to the raising of,

precast concrete roofs and upper iioors without embodying columns in thesection of the oor or roof that is being ice raised into place. The useof jacks to raise concrete slab roofs has been suggested, but in allapplications known to the applicants the jacks have been located at theplaces where there is to be a column, and in fact in many instances thejack itself is left permanently in position to serve as the column. Inthis manner there is obtained a free span of roof or oor simply bylifting the slab from its side and/ or end edges.

The invention contemplates raising precast second, third and more upperfloors as well as the roof, from the stationary oor beneath. Forexample, where a two story house is to be built, the ground or irStfloor slab is poured in place and allowed to harden. Then the second oorslab is poured onto the top of the ground slab and raised to ultimateposition when hardened according to the manner, below described, andthen the roof slab is poured onto the raised second floor slab and theroof slab when hardened is raised by the jacks reacting from the nowstationary second iioor slabs. In this manner the invention isapplicable to multi-story buildings.

The invention provides the only known method which can be adapted to anylocation or condition of terrain, and for raising the upper floor orroof into place without the location of the jacks being determined bycolumns to support the floor or roof.

The invention provides particular economy of building whichis especiallytrue for small low cost houses. The jacks may be used repeatedly andthey eliminate the hitherto high cost of expensive framing and temporarysupport structures that had to be torn down and rebuilt for eachsuccessive oor or roof.

The invention will now be described in its simplest embodiment which isthe erection of a one story building having a concrete oor and aconcrete roof. It will be appreciated that for a two story building forexample, instead of a roof slab, a second floor slab would be separablyprecast onto the rst oor slab, and then the roof slab similarly precastonto the raised second iioor slab.

The present invention in its preferred embodiment provides an entirelynovel construction involving the following procedure:

First a slab is poured to serve as the ground or first floor. Then,within 24 hours after the first floor is in place, or later if desired,coating is formed or placed over the top surface of the floor. One formof this coating may -be for example a water tight tough polyethylenesheet or like unitary covering placed over the entire slab iioor. Thiscovering is pulled tight to eliminate wrinkles. After the sheet is onthe floor, wire mesh or reinforcing means of appropriate size is placedon top of the covering. Alternatively to the use of such removable sheetcoverings the coating upon the top surface of the floor slab maycomprise a layer of some paint or wax-like liquid or other waterimpervious material spread like paint over the entire top surface. Sucha coating, like the removable sheet type of covering, prevents the wetyconcrete poured onto it from adhering to it, and in the claims thiscoating or covering will be referred to as a layer of material effectiveto prevent adherence of the -wet concrete to the Hoor beneath and topermit separation of the slabs by lifting the upper slab. The plasticsheet covering is preferable for residential dwellings because itprovides a smoother bottom surface on the formed upper slab. v

The wet `concrete is then poured on top of the covering sheet and thereinforcing is imbedded in it, the concrete ibeing of such thickness ashas been determined appropriate for the given structure of roof or upperoor slab. At desired places there are inserted at given intervals boltswith special fasteners made especially for use in concrete.

After the concrete has set for a given number of days, depending on thetype of concrete that was used, bar joists are usually placed on the topof the upper poured slab and secured to it by means of the bolts thatwere imbedded in the concrete.

To raise the roof or upper floor slab there is placed on each long sidea given number of special coacting screw type jacks of a character to bedescribed in detail, varying in length from 1() to 12 feet. Thesespecial jacks may be placed on foot centers, so in raising a roof 30feet long, there would be a total of seven jacks on each side. Any-center spacing practical may be used. No jacks are placed at the end ofthe buildings for most operations but in some instances added jacks willbe used at the ends of the slabs as well as the long sides, and thebottoms of the jacks rest on the footing of the slab oor. The jack liftrods on each side of the building are con nected as by a sectionaltubular shaft and gearing. At the top of each jack lift rod is a wormgear, which worm .gear is operated by means of the tubular shaft. On thedirst jack at either end of the building and on each side of thebuilding, there' is a pulley that is operated by means of a belt. Thisbelt leads from the pulley on each side of the house to separate smallgasoline or electric motors located on the ground. Alternatively onlyone motor may be used and the two pulleys connected by a belt to bedriven together for more accurate synchronization of Ithe lift effort atboth sides.

The jacks are spaced so that they lift the slab with a practicallycontinuously distributed effort under the edges of the slab on each sidethereof. Each jack sustains as near as possible a uniform load andexerts an equal upward push on the slab being lifted. As a result thereis little or no torsional or bonding strain in the slab being lifted andit does not crack.

The roof orupper vfloor slab is raised usually about a foot or moreabove the desired height of the wall below it. 'Ihe jack holds theraised slab at this height until the walls below are completed. Then bysimply reversing the jacks, the slab is lowered onto the wall and thefreed jacks are removed. Specific and novel structure including specialjacks will be described for carrying out the invention. Y l

The major object of this invention therefore is to prolvide'a novelsimple and economical method for constructing a building wherein a roofor upper floor slab is cast in overlying relation to the floor beneathand then raised to permit building of the walls beneath it.

Another object of the invention is to provide a novel method of buildingconstruction wherein a precast roof or upper floor slab is lifted from astationary floor slab by a special jack and drive construction which isentirely removed when the roof or upper oor slab has been lowered ontowalls erected on the lower floor slab.

llt is a further object of the invention to provide a novel method lofbuilding construction wherein floor and roof slabs of concrete or thelike are separatively cast one above the other, the upper oor or roofslab lifted to just `above desired side wall height, the side wallsbelow it erected, and then the upper floor or roof slab lowered onto theerected walls.

A further object of the invention is to provide a novel method ofbuilding construction wherein a door slab is cast on the ground andcovered with relatively smooth layer that does not adhere to wetconcrete and the upper floor or roof slab is cast over the top of saidlayer. The vlayer may be painted on or may be a sheet of such characterthat it is readily removed when the slabs are separated vertically.

It is a further object of the invention to provide a novel method andapparatus for building construction wherein a cast roof or upper oorslab of concrete or the like as raised with respect to a floor slab withuniformly distributed lifting elfort to reduce strains in the risingslab.

A further object of the invention is to provide a novel arrangement ofprecast upper iloor or roof slab lifting jacks for buildingconstruction.

It is another object of the invention to provide a novel jack structurefor lifting cast floor or roof slabs and the like.

Another object of the invention is to provide a slab lifting jack ofnovel construction having a special lift and drive arrangement.

It is a further object of the invention to provide a novel drivearrangement for a plurality of slab lifting jacks wherein all areactuated at substantially the same rate to exert uniform lift effortalong the slab.

Further objects of the invention will appear as the description proceedsin connection with the appended claims and the annexed drawings wherein:

FIGURE 1 is a substantially perspective view of a roof slab;

FIGURE 2 is a substantially perspective View showing pre-cast oor androof slabs as separated by a non-adherent layer in the form of apolyethylene sheet;

FIGURE 3 isa section essentially through superposed pre-cast oor androof slabs showing the separating sheet and the anchors for attachingthe 'girders to the roof slab;

FIGURE 4 is a top plan view showing the jacks aligned along oppositesides of a roof slab and connected to be driven for lifting the slab;

FIGURE 5 is a substantially perspective view showing the entireoperation in progress with a roof slab partially lifted by the jacks;

FIGURE 6 is a fragmentary substantially perspective section showing -theinterlocking arrangement of the edge of a roof slab with the top of theerected side wall;

FIGURE 7 is an enlarged perspective View showing a. jack according to apreferred embodiment of the invention with a roof slabl shown partiallyraised;

FIGURE 7A is a fragmentary detail showing the jack as applied to theslab prior to raising the slab;

FIGURE 8 is a section substantially on line 8--8 of FIGURE 7;

FIGURE 9 is -an enlarged perspective View showing thekdrive shaftcoupling and gearing at the top of each Jiac FIGURE 10 is a sectionthrough the drive connection and thrust bearing at the top of each jack;

FIGURE 11 is a section showing another form of precast superposed oorand roof slabs wherein the roof slab slightly overhangs the oor slab;

FIGURE l2 is -an end elevation of a jacking arrangement for lifting aroof or upper slab which has been cast over a floor slab wherein jacksbased on the floor slab are .connected to lift girders secured to theroof slab;

FIGURE 13 is a side elevation of the arrangement of FIGURE l2 showingthe parts as they appear when the yroof slab has been partially raised;

FIGURE 14 isan elevation partially in section showing the jack drive andthrust bearing arrangement at each jack unit of the assembly of FIGURES12 and 13;

FIGURE 15 is a top plan View of a roof or upper oor slab yaccording toanother embodiment;

FIGURE 16 is a perspective view showing a jack for vuse in lifting-thecentral part of this slab;

Achored in situ.. Then, after the floor slab 11 is hardened,

Y .its top surface is either covered by a removable layer such as a thinsheet 12 of tough flexible smooth moisture resist ant and imperviousmaterial of such characteristics that it will closely overlie the ioorslab and permit the flat concrete roof slab 13 to be poured onto it andto maintain the roof slab 13 isolated from iioor slab 11 until the roofslab has hardened, or the top surface is coated with a xed layer such asa wax-base paint that will not adhere to wet concrete. Sheet 12 is drawntight to eliminate wrinkles. For inexpensive house construction theslabs are usually substantially rectangular, although any suitablevariation in form may be provided. Slab 13 may of course be a secondiloor slab instead of a roof slab.

During the casting of each slab 11 and `13 suitable Wire or rodreinforcement may be incorporated within them and reference to theseslabs herein includes both reinforced and non-reinforced slabs. Also,during the casting of the slab 11, a series of rows of anchor members 14are cast therein, and these may be for example headed bolt-like membershaving threaded Shanks projecting above to the at top surface of slab13. Any suitable fasteners may be used as anchors.

Suitable forms for casting the slabs are shown at 15 in FIGURE 3 andthese may be conventional. Care should be taken in this embodiment thatthe roof or other slab to be raised should have no appreciable overhangrelative to the slab below it. Usually, see FIGURE 7A, the longer sideedge of the rectangular oor slab 11 is formed with recessed edgeshoulder means 20 which may be either a continuous groove or a series ofthem to accommodate the various jack bases to be later described.Alternatively this shoulder could be formed in the roof slab as adownward recess or the roof slab, by using suitable forms, may be castto overhang the side edge of the floor slab as will be evident in theform of FIGURE l2. In any event, whether shoulder or overhang isprovided, arrangement is made for jack bases to seat on the floor slab11 along its side edge and enable the lift members of the jacks to litunder the side edges of the slab to beI raised.

After the slab 13 has hardened the forms are removed and a series ofjack assemblies 16 are arranged along the opposite long sides of theslabs, as shown in FIGURES 3 and 5. As shown in FIGURES 7 and 7A, eachjack assembly comprises a base 17 of rigid angle iron that has ahorizontal top leg 18 seated on theI oor slab at shoulder 20, a verticaldepending leg 19 engaging the side of the floor slab above ground level,and a horizontal outwardly extending leg 21 which may or may not .becoextensive with the length of the other legs. Two tubular sockets 22and 23 are formed on leg 21 to receive the lower ends of vertical pipes24 and 25 which are the rigid frame side members of each jack assembly.

At the upper ends of each jack assembly a rigid frame channel 26 i-sfixed as by welding 'across the tops of pipes 24 and 25. Near theirlower ends pipes 24 and 25 are rigidly joined by `a brace 27 usuallywelded to them. Sev-v eral of Ithese braces may be used along the pipesas desired.

The lift member iof each jack assembly 16 comprises a U-shaped elevatorframe 28 having a horizontal bridge 29 and spaced upright vertical sideplates 31 and 32. vThe lower ends of plates 31 and 32 are rigidly joinedby a plate 33 preferably welded thereto, and a length of rigid angleiron 34 has its vertical leg 35 removably secured to plate 33 as bybolts 35a. The horizontal leg 36 extends under Ithe edges of the roofslab as show-n in FIGURE 7A, which is the start of the lift operation,and FIGURE 7 shows the roof slab partially lifted.

Each elevator 28 is laterally supported and guided for vertical movementalong pipes 24, by Iupper `and lower freely rotatable roller assemblies.The lower roller assembly consists of an axle 37 with rollers 38 atopposite ends, and the upper roller assembly consists of an axle 39 withrollers 41 at opposite ends. Axles 37 and 39 are freely journalled inplates 31 and 32. Alternatively the axles may be fixed and the rollersfreely rotatable. As shown in FIGURE 8, axles 37 and 39 are parallel andarranged in vertically displaced relation on opposite sides of the pipeframes 24, 25. The rollers 38 and 41 are so shaped as to smoothly rollalong the cylindrical pipes and they are shaped and arranged to preventany appreciable yshift or tilt of elevator 28 either toward or away fromthe roof slab or along the roof slab, and the mot-ion of elevator 28 isessentially only vertical.

Secured to the elevator bridge 29 is an inverted U- shaped bracket 42having a horizontal bridge 43- and depending parallel legs 44 and 45welded at their lower ends to elevator bridge 29. As shown in FIGURE 8this bracket is within the lateral contines of axles 37 and 39 and doesnot interfere with them. Centrally of bracket bridge 43 is a dependingrigid hollow boss 46 that is internally formed with a spiral screwthread. A Vertical threaded rod 47 is rotatably threadedly engagedwithin boss 46 and extends below to seat freely rotatably within a guideor step bearing 48 on the base leg 21.

A-t its upper end rod 47 enters a gear assembly 49 that comprises a Wormgear 51 having its hub keyed to rod 47 at 52 and welded thereto at 53 soas to be xed axially -and non-rotatably on rod 47. The gear assembly issupported on the upper race 54 of a roller thrust bearing assembly 55having its lower race 56 fixed to a platform 57 secured on the top ofchannel 26 as by bolts 58. Thus rod 47 extends freely through `channel26 and is effectively suspended therefrom. Thrus-t bearing 55 may bearthe entire weight of the rod 47 and the gear assembly and lower bearing48 may simply be a guide. If desired lower bearing 48 may be omitted.

Platform 57 also carries a Worm 58 meshed with gear 51 and fixed on ashaft 59 journalled in spaced supports '52, 53 on the platform so as tobe restrained against longitudinal movement. A cover for platform 57open only to pass the opposite ends of shafts 59 may be provided.

Referring .now to FIGURE 4 it will be seen that shafts '59 of therespective jack assemblies are connected nonrotatably at opposite endsto shaft sections 61. Preferably each shaft 59 has at opposite endsfixed radial pins 62 and the shaft sections 61 are hollow andlongitudinally slotted at 63 to be telescoped over and lockednon-rotatably with shafts '59. This allows a considerable variation inspacing of the jack assemblies along the sides of the slabs. Universaljoints are provided where the shafts are angularly related.

At one end of each side of the house a pulley 64 (FIG- URE 5) is fixedon the shaft 59 and this pulley is drive connected by a belt 65 to apulley 66 on an electric motor assembly 67 mounted on a platform 68.Alternatively motor 67 may be an internal combustion motor assembly.Platform 68 is effectively pivoted at 69 and it will be seen that in theillustrated position of FIGURE 5 i-t maintains belt 65 taught to drivepulley 64 but when tilted clockwise it will loosen the belt andinterrupt the drive. This provides a simple variable speed drive andclutch to pulley 64. Alternatively instead of supplying two motorassemblies 67 connected to the respective pulleys 64, only one motor 67of suitable size is used connected by belt to one pulley 64, and thepulleys 64 are connectedr in synchronism by a chain and sprocket drive.

Suitable rigid braces 71 may be provided to maintain the jack framesvertical.

In practicing the invention, the floor and roof slabs are cast ofconcrete spaced by the polyethylene sheet 13 or other layer. Then aseries of jack assemblies 16 is arranged on each long side of the slabsso that the base of each jack seats on the iioor slab while the leg 36of each extends under the edge of the roof slab. Usually the jackassemblies are spaced apart about four to six feet and braced inposition. Then each jack assembly is adjusted by turning its shaft 59until leg 36 engages the underside of the roof slab under load. Then theshaft sections 61 are applied to interconnect all of the shafts `59 oneach side and pulley 64 is mounted and connected to the motor assembly.Motors 67 are energized to drive each pulley 64 so that all shafts 59 ateach slide areA simultaneously driven at the same rate and equal anduniform lift forces are exerted by legs 36 all along both sides of thehouse. Any suitable means may be provided for synchronizing the drive atboth sides of the house but in practice good results have been obtainedby having two operators work together on opposite sides of the buildingwatching suitable level indicators as fthe roof slab rises. FIGURE showsthe roof slab partially raised.

'I'he roof slab 13 is raised by the foregoing arrangement to a pointabout a foot above the desired height of the side Walls, and held thereby the jacks. In FIG- URE 5 are shown a series of auxiliary jacks 72which may consist of telescoped threadedly connected relativelyrotatable rods 73,` and 74 adapted to be extended as the roof slab israised to support the intermediate sections of the roof slab and keep itfrom sagging.

When the roof slab 13 has been fully raised the side walls are built upon the floor slab 11 as shown at 75 in FIGURES 5 and 6 to the desiredheight. The wall bricks at the top of each wall are of the lintel typehaving `a continuous longitudinal groove 76 into which fresh concrete ispoured. Then the jacks are reversed to lower the roof slab 13 onto thewalls. There is imbedded in the concrete roof before the concrete sets,iron reinforcing rods 77, the bottoms of which are bent so as to` layflat on top of the concrete -lloor upon which the roof is poured. Thenwhen the roof is lifted, these rods which are usually l foot to 18inches long, are simply bent down from the roof and fixed so they willmesh into the cavity 76 of `the lintel block that forms the top courseof the walls. Concrete is then poured into the cavity of the lintelblock and the roof is lowered and allowed to set holding the rod inplace.

The jack assemblies 16 may be entirely removed when the roof slab hassettled onto the walls which now support it. 'I'he polyethylene sheet 12can be removed as lsoon as the slab 13 is jacked a small distance,leaving Vsmooth floor and ceiling surfaces.

Referring to FIGURES 11-14 another structurally different embodiment ofthe invention is illustrated.

FIGURE ll shows the cast floor slab 11, the polyethylene spacer sheet 12and the cast roof slab 13, after the casting forms have -been removedand -both slabs are hard and ready for the roof slab raising. The rststep here is to :mount a number of cross girders S0 parallel to theshort side of the roof slab. The lower rail 81 of each girder hasopenings to receive the anchor bolts 14 imbedded in the roof slab andnuts 82 are drawn tight to fasten a series of these parallel girders 80across the top of the roof slab. Any other suitable means may be used todetachably secure the girders to the Slab 13.

It will be noted that the roof slab slightly overhangs the floor slabalong the long sides, and along horizontal -surfaces 83 are laid bottomjack support rails 84. At -spaced points along rails 84 are attached aseries of jack bases 85, one below the end of each girder 80. Uprisingfrom each jack base is an outwardly open vertical channel 86, and theupper ends of channels 86 on each side are rigidly secured together byan upper horizontal rail 87. Suitable wire braces 88 having adjustableturnbuckles y89 stiffen and align the frame comprising rails 84 and 87and channels 86.

A jack lift member or elevator 91 is vertically slidably mounted on eachchannel 86, and each elevator 91 has an internally threaded boss 92 anda flat horizontal platform 93. A horizontal rail 94 is rigidly securedacross all of the platforms 93 on each side of the slabs, the rail beingapertured in places to freely pass the upright channels 86. Rail 94 isadapted to be located under and in supporting relation to all of theends of top rails 95 of the girders 80.

Enclosed by each channel 86 is a vertical threaded rod 96 threadedlypassing through boss 92 and having its lower extending down to the jackbase 85. The upper end of rod 96, FIGURE 14, projects through an openingin rail 87 and has secured thereto above rail 87 a gear assembly 97iiXed to the upper race 98 of a thrust ball bearing 99 having its lowerrace 101 secured to rail 87. The weight of rod 96 and the gear 97 varethus suspended. Also journalled on rail 87 at the upper end of each rod96 is a worm 102 meshed with gear 97, and each worm is mounted on ashaft 103 connected at opposite ends to the adjacent shaft 103 bytelescoped extensible hollow shaft sections 104 that permit variablespacing of the jack assemblies along the slabs.

Usually the jack frames along opposite sides of the slabs may be rigidlyconnected at their upper ends by horizontal end rails 105 and associatedturnbuckle tightened brace wires 106 for mutual support and alignment.

In this embodiment, as well as in FIGURE 5, a pulley 64 is attached tothe end shaft at the top of the jack frame and when pulley 6'5 is drivenby the electric motor as in FIGURE 5 all of the threaded rods 96 aresimilarly rotated to rail 94.

In practice, after the roof and oor slabs are cast, the jack assembliesare positioned and braced and each jack individually adjusted tosubstantially equal load by rail 94 which supports the ends of girders80 and therefore the weight of the roof slab suspended from the girders.The roof slab is raised to the desired height, the walls built up andthe roof slab lowered onto them as in the preceding embodiment.

Referring back to FIGURE 4 it will be noted that a series of girders arebolted to the roof slab as described for the embodiment of FIGURE l1.These primarily stiften and reinforce the slab for lifting. These mayalso be attached to certain jack assemblies as in the FIG- URE 12embodiment so that a combination of both jack structures could be usedfor raising the slab 13. One arrangement that has proved successful isto use the direct lifting arrangement of FIGURES 1-10 at the ends of theslabs while using at the central portions of the roof slab the liftingmeans of FIGURE 12 where the jacks act on the girders 80, that reducingthe possibility of roof slab sag.

FIGURES 15-18 illustrate an arrangement which is a Variation of theembodiment of FIGURES l-lO. As shown in FIGURE 15 the jack assemblies 16are arranged all along the long sides of the slabs and the lift membersof these jack assemblies are engaged with the roof slab as in FIGURESl-10. Some installations, however, may require additional lifting at thecenter of the roof slab and in this arrangement a series of jackassemblies 107 are provided for this purpose, disposed along thelongitudinal centerline of the house.

Each assembly 107 comprises a at base 108 adapted to seat directly onthe sheet 12 overlying the hardened cast floor slab 11. Rigid with thebase are two hollow socket bosses 109 and 111 adapted to removablyreceive the jack pipes 24 and 25. A rigid plug 112 upstands from base108 midway between the bosses. Also provided in base 108 are apertures110 adapted to removably mount upright inserts 113 that are externallyserrated at 114 and internally threaded at 115. In practice the exposedsurfaces of base 108, bosses 109 and 111 and plug 112 are coated withgrease or polyethylene to prevent concrete poured on to form the roofslab from sticking to the base 108. 'I'he height of bosses 109 and 111and plug 112 is equal to the thickness of the roof slab 13, and theyform holes through that slab to permit passage of pipes 24 and 25 andthreaded rod 47 as the slab rises.

The threaded rod 47 which is suspended from channel 26 in the samemanner as in FIGURE 7 has threaded engagement with a lift bar 116apertured at both ends to permit passage of bolts 117 adapted to bethreaded into inserts 113 that are cast with slab 13. Rod 47 alsoextends through the slab being raised.

The shafts 59 of the worm and gear drive at the top of channel 26 areconnected by telescoped extensible shaft sections like those at thesides and the compound shaft is driven by a separate motor to raise allthree bars 116 at the same rate that the outside edges of the slab 13are being lifted by jack assemblies 16.

When the roof slab has been lowered onto the walls the jack assembliesare detached by removing bolts 117 and then pulling the rods out throughthe roof. The sockets 109 and 111 and inserts 113 are filled and locallysmoothed over.

The foregoing arrangement has especial advantage where there are notstiffening girders attached across the top of the roof slab 13.

In all of the foregoing embodiments it will be appreciated that thedisclosure of forming and raising a roof slab applies equally well tothe forming and raising of intermediate oor slabs in a multi-storybuilding. Where the building has more than one story the second floorslab is cast onto the ground floor slab and raised to position, and thenext slab (third floor or roof) is cast onto the raised second oor whichnow supports the jack assemblies.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the .appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. A slab lifting jack construction for raising and lowering a slabstructure with respect to a stationary rigid oor after the slabstructure has been fabricated in directly overlying relation to saidfloor and comprising at least two jack lifting assemblies disposed atoppositely directed sides of said Islab structure, each of said jacklifting assemblies comprising -a plurality of side-by-side laterallyspaced apart jacks and actuating means for said jacks, each of saidjacks comprising a base detachably seatable upon the upper surface ofsaid floor, an upright frame extending rigidly for substantially theheight at which said slab structure is desired to be permanentlysupported above said floor when said assemblies are removed, a liftmember vertically slidably mounted on said frame between a lowermostposition directly overlying said oor adjacent said base and an upperposition at the upper end of said frame and having a part insertableunder a portion of said slab structure and being detachably connected tosaid slab structure for lifting and lowering said slab structure, saidpart being positionable sufficiently close to said floor by verticaldisplacement of said lift member to enable said part to be insertedunder said portion of said slab structure when said slab structure isinitially resting on said floor, a vertical threaded rod rotatablymounted on said frame and extending to the top thereof, means on saidlift member providing a threaded connection with said threaded rodenabling said lift member to be vertically slidably displaced along saidframe by rotation of said threaded rod in either direction; saidactuating means comprising shaft means rotatably carried by the framesof said jacks at the upper ends thereof in transverse relation to thethreaded rods of said jacks and gear means individual to each threadedrod of said jacks and drivingly connecting said shaft means with eachthreaded rod of said jacks adjacent the upper end of said threaded rodto similarly rotate the threaded rods of said jacks simultaneously; anddrive means associated with said assemblies for rotating the shaft meansof said assemblies to impart rotation to the threaded rods of said jacksin a selected direction thereby enabling the jacks of said assemblies toexert lifting and lowering movement to said slab structure, said jacklifting assemblies engaging said oor and said slab structure solely bysaid detachable seating of the base of each of said jacks and by thedetachable connection of the ylift member part of each of said jackswhereby said jack lifting assemblies are each removable from said floorand said slab structure as a unit.

2. The jack construction defined in claim 1 wherein said frame comprisesa pair of spaced apart parallel erect guide members each having acylindrical periphery and with said threaded rod extending in parallelrelation between said guide members, said lift member having a supportsection carrying said threaded connection to said threaded rod anddisposed between said guide members, at least two shaft members carriedby ysaid support section and extending transversely of said guidemembers on opposite sides thereof, and a pair of rollers carried by eachof said shaft members and respectively engaging said guide members toguide said support section for linear vertical displacement between saidguide members.

3. ln the apparatus defined in claim 1, said shaft means comprising aplurality of adjustable length sections to provide for different spacingbetween the jacks.

References Cited in the file of this patent UNITED STATES PATENTS1,102,232 Benedict July 7, 1914 1,243,360 Stoudt Oct. 16, 1917 1,440,968CreSebrO Jau. 2, 1923 1,477,790 Townsend Dec. 18, 1923 2,043,140Wilmesherr June 2, 1936 2,187,283 Scheutz Ian. 16, 1940 2,343,993 NaylorMar. 14, 1944 2,504,201 Johnson Apr. 18, 1950 2,516,318 Hawes July 25,1950 2,605,540 Kroll et al Aug. 5, 1952 2,650,795 Bell Sept. 1, 19532,720,017 Youtz Oct. 11, 1955 2,721,724 Bottorif Oct. 25, 1955 2,758,467Brown Aug. 14, 1956 2,794,242 Evers et al June 4, 1957 2,871,544 YoutzFeb. 3, 1959 FOREIGN PATENTS 658,203 France Jan. 22, 1929 613,403 GreatBritain Nov. 25, 1948 1,004,783 Germany Mar. 21, 1957 OTHER REFERENCESLift Slab Method in `Construction News Bulletin Sept. 19,1953, pages4-8.

